Low-density Water Research Articles

Experimental evidence of low-density liquid water upon rapid decompression

Water is an extraordinary liquid, having a number of anomalous properties which become strongly enhanced in the supercooled region. Due to rapid crystallization of supercooled water, there exists a region that has been experimentally inaccessible for studying deeply supercooled bulk water. Using a rapid decompression technique integrated with in situ X-ray diffraction, we show that a high-pressure ice phase transforms to a low-density noncrystalline (LDN) form upon rapid release of pressure at temperatures of 140-165 K. The LDN subsequently crystallizes into ice-Ic through a diffusion-controlled process. Together with the change in crystallization rate with temperature, the experimental evidence indicates that the LDN is a low-density liquid (LDL). The measured X-ray diffraction data show that the LDL is tetrahedrally coordinated with the tetrahedral network fully developed and clearly linked to low-density amorphous ices. On the other hand, there is a distinct difference in structure between the LDL and supercooled water or liquid water in terms of the tetrahedral order parameter.

Exploring the behaviour of water in glycerol solutions by using delayed luminescence.

The crucial role of water in the engine of life have encouraged many researchers in studying, both theoretically and experimentally, the possible “structure” of water. Many properties of water have been related to the interplay between two distinct and interconverting structural species, namely the low-density water (LDW) and the high-density water (HDW). Supported by the results obtained with other aqueous solutions, this paper deals with the possibility of using the ultra-weak delayed luminescence (DL) to investigate water structuring in a mixture with glycerol, characterized only by hydrogen bonds between the various molecules. Spectral and temporal characteristics of DL decays give information on the two components of the mixture, by evidencing the contribution of water at glycerol concentrations close to the values used in cryopreservation. DL results have shown a correlation with LDW clusters size as determined by other researchers on the basis of neutron diffraction experiments and computational modelling, as reported in Literature.

Graphene Oxide Admixed Aerated Concrete Composite with Carbon Fibres

Concrete is the widely used construction material and research focus is towards customizing the mixture proportion to suit the application for various construction facilities. Advancement in construction industry has resulted in fast track construction facilities with the use of precast structural elements. Lightweight concrete is gaining importance due to the popularity of prefabricated construction. This paper highlights the optimized mixture proportion of aerated concrete composite with certain chemical and mineral admixtures so that it can be suitably used for precast structural elements. Aluminium powder was used as the aerating agent. Lime powder of about 30% by weight of cement was used to facilitate the aeration process. Lime reacts with aluminium powder liberating hydrogen gas which is responsible for the air voids in concrete. Fly ash class F was used as replacement for sand by 20%. The sand used for this concrete was pulverized and the fraction passing 1.18 mm sieve was used for the concrete. Since the mixture proportion is a multivariable process, statistically designed experiments using central composite design of response surface methodology was used to design the trial mixes. The significance of the interacting factors and the validity of experimentation were analyzed using ANOVA analysis. The strength properties and durability tests were performed to access the characteristics of the material. The density of the concrete was 1285 kg/m3 .The compressive strength obtained was 27.5 MPa, the tensile strength was 2.89 MPa and flexural strength was 3.4 MPa. Chopped carbon fibres and graphene oxide were admixed to the concrete and it was observed that there was 13% increase in the compressive strength when 0.05% of graphene oxide was added. Also carbon fibres increased the flexural strength of the concrete bridging the cracks that were formed when load was applied. Response surface graphs were drawn for all the characteristics that were studied. The significant interaction effects were assessed for all the observed characteristics. There is a general view that aerated concrete being a porous material will not be durable in terms of performance. Hence durability tests like carbonation test, concrete impermeability test and rapid chloride penetration tests were performed to access the durability of the material. It was observed that there were isolated pores and hence the durability of the concrete was the same as conventional concrete. Hence optimized mixture ratio was obtained for low density, high strength and low water permeability. This material can be potentially used for the fabrication of precast structural components so that the process of handling these members will be easy due to the reduced weight of the concrete. Also it has been reported that aerated concrete has good acoustical and thermal insulation properties.

Dosimetric verification of small fields in the lung using lung-equivalent polymer gel and Monte Carlo simulation.

The main purpose of this study was evaluate a polymer-gel-dosimeter (PGD) for three-dimensional verification of dose distributions in the lung that is called lung-equivalent gel (LEG) and then to compare its result with Monte Carlo (MC) method. In the present study, to achieve a lung density for PGD, gel is beaten until foam is obtained, and then sodium dodecyl sulfate is added as a surfactant to increase the surface tension of the gel. The foam gel was irradiated with 1 cm × 1 cm field size in the 6 MV photon beams of ONCOR SIEMENS LINAC, along the central axis of the gel. The LEG was then scanned on a 1.5 Tesla magnetic resonance imaging scanner after irradiation using a multiple-spin echo sequence. Least-square fitting the pixel values from 32 consecutive images using a single exponential decay function derived the R2 relaxation rates. Moreover, 6 and 18 MV photon beams of ONCOR SIEMENS LINAC are simulated using MCNPX MC Code. The MC model is used to calculate the depth dose water and low-density water resembling the soft tissue and lung, respectively. Percentages of dose reduction in the lung region relative to homogeneous phantom for 6 MV photon beam were 44.6%, 39%, 13%, and 7% for 0.5 cm × 0.5 cm, 1 cm × 1 cm, 2 cm × 2 cm, and 3 cm × 3 cm fields, respectively. For 18 MV photon beam, the results were found to be 82%, 69%, 46%, and 25.8% for the same field sizes, respectively. Preliminary results show good agreement between depth dose measured with the LEG and the depth dose calculated using MCNP code. Our study showed that the dose reduction with small fields in the lung was very high. Thus, inaccurate prediction of absorbed dose inside the lung and also lung/soft-tissue interfaces with small photon beams may lead to critical consequences for treatment outcome.

Effects of heating rates and SBE loading on sintered properties of spent bleach earth/recycled glass composite

The purpose of this study is to investigate the influence of different heating rates on the properties of glass ceramic composite (GCC) at different spent bleach earth (SBE) loadings. GCC was prepared using SBE and recycled soda lime silicate (SLS) glass. The particle size of SLS glass was approximately <45μm. The GCC was formed by uniaxial dry pressing at weight fractions of SBE loading of 40 wt. %, 45 wt. %, and 55 wt. %. The GCC was then sintered at different heating rates of 2 oC/min, 4 ˚C/min, 6 oC/min and 8 ˚C/min at 700 oC of sintering temperature. The GCC specimens were analysed in terms of their physical properties, while crystalline phase and microstructure were characterized using X-Ray diffraction and scanning electron microscope (SEM), respectively. The results from X-Ray diffraction pattern showed that quartz and wollastonite phases were formed with no major changes on the phases as the heating rate increased. The results indicate that the variation of heating with 2 oC/min interval does not give a remarkable result of physical properties on GCC. High loading of SBE sintered at 2 oC/min of heating rate produced low water absorption, density and porosity. SEM analysis showed that the physical properties and crystalline phases were correlated to the SBE loading and changes in the heating rate. The study concluded with the prospect of continuing the work of optimisation on schedule heat treatment at sintering temperature regimes.

Adsorption of aquaculture pollutants using a sustainable biopolymer.

Intensive aquaculture needs to adopt techniques that are able to contribute towards sustainability. Closed systems that employ water recirculation can combine intensive production with environmental sustainability, since there is no exchange of water or discharge of effluents into the environment. In order to achieve this, effective filtration systems are required to ensure that the water quality is satisfactory for the cultivation of aquatic organisms. Chitosan, an industrial waste material derived from crustacean farming, is a renewable natural material that is biodegradable and possesses adsorbent characteristics. In this work, chitosan foam was incorporated in filters and was evaluated as an adsorbent of aquaculture pollutants, adding value to the material and at the same time providing a use for industrial waste. The foam was characterized by scanning electron microscopy and energy dispersive spectroscopy, apparent density, and water absorption capacity. It was used to remove ammonia, nitrite, orthophosphate, and turbidity from aquaculture effluents. The foam consisted of a bilayer with smooth and porous sides, which presented low density, flexibility, and high water absorption capacity. The best proportion of the foam, in terms of the mass of foam per volume of solution (%mv-1), was 0.10, which resulted in removal of 32.8, 57.2, 89.5, and 99.9% of ammonia, nitrite, orthophosphate, and turbidity, respectively. This biopolymer produced is biodegradable, and when saturated with organic compounds from aquaculture, and no longer suitable for reuse as a filter material, it can be employed as a fertilizer, hence closing the sustainability cycle of the aquaculture production chain.

High-Bulk Water Dispersible Paper-Based Composites

Paper sheets having a lignin content of ~12% by mass (kappa = 78) containing 50% fines prepared from slurries, soy lecithin, and β-cyclodextrin display an unusually low density (i.e., high bulk) and rapid water dispersibility. It is postulated that lecithin adsorbs to fiber lignin and the cyclodextrin associates with the lecithin. The cyclodextrin subsequently expands the sheet in the z-direction because it is a hydrophilic species embedded within a hydrophobic matrix. The sheet is water dispersible owing to its high bulk, and disintegrates at nearly the same rate as toilet tissue. Potential applications include packaging or thermal insulation products such as coffee sleeves that can be safely flushed away in water after use.

Thermodynamic properties of dilute hydrogen in supercritical water

A thermodynamic model is developed to calculate the fugacity coefficients and partial molar volumes of hydrogen at infinite dilution in water at 647.1–2000 K and pure water densities between 0 and 1500 kg m−3. The model is based on the predicted values of DCFI (the dimensionless integral of the infinite dilution hydrogen - water direct correlation). Values of DCFI at low water densities are calculated from accurately known second cross virial coefficients; at high water densities predictions are based on the relations from the theory of a mixture of hard spheres; DCFI values at intermediate water densities are interpolated using a variant of corresponding-states correlation. Predicted values of the hydrogen fugacity coefficients at infinite dilution in water are compared with experimental data and results of the literature equations of state. The included Excel spreadsheet allows calculations provided that values of T, P, ρ1∗, and κT for pure water are entered by a user.

Effect of combined static magnetic field and cold water shock treatment on the physicochemical properties of cucumbers

Based on the mechanism of temperature shock treatment and electromagnetic effect for food preservation, this paper developed a novel food preservation method by combining static magnetic field with low magnetic flux density and low-temperature water shock to process the fresh postharvest vegetable. Compared with the single cold-water shock treatment (CST, Tw = 2 °C, τ = 40 min), the static magnetic field and cold-water shock treatment (SMCT, B = 70 Gs, Tw = 2 °C, τ = 40 min) caused an increase of cooling-rate of cucumbers' tissues during treatment. Weight loss of SMCT was also lower than that of CST during storage. Furthermore, decay incidence and color difference of SMCT were about 40.2% and 10.6% lower than that of CST. Activities of catalase and superoxide dismutase for SMCT were higher than that of CST, which caused a reduction of malondialdehyde. Experimental results confirmed that SMCT had a positive influence on pre-cooling, preservation quality and physicochemical properties of cucumbers.

Effect of solute nature on the polyamorphic transition in glassy polyol aqueous solutions.

I examined the polyamorphic behavior of glassy dilute aqueous solutions of polyols (ethylene glycol, glycerol, meso-erythritol, xylitol, and D-sorbitol) under pressure at low temperatures. Although the volume change of the glassy aqueous solution varied continuously against pressure, the rate of the volume change appeared to vary discontinuously at the onset pressure of the gradual polyamorphic transition. It is thought that low-density liquid-like solvent water and high-density liquid-like solvent water coexist during the transition. Moreover, the existence of a solute induces the shift of polyamorphic transition to the lower-pressure side. The effect of a solute on the polyamorphic transition becomes larger in the order ethylene glycol, glycerol, meso-erythritol, xylitol, and D-sorbitol. Therefore, the solute can become a variable controlling the polyamorphic state of liquid water. This experimental result suggests that the metastable-equilibrium phase boundary between the low-density and the high-density amorphs for pure water is likely to be located at 0.22-0.23 GPa at about 150 K, which is slightly larger than the previously estimated pressure. Moreover, the solute-nature dependence on the polyamorphic transition seems to connect to that on the homogeneous nucleation temperature of polyol aqueous solution at ambient pressure. The region in which a low-density liquid appears coincides with the region in which the nucleus of ice Ih appears, suggesting that the formation of a low-density liquid is a precursory phenomenon of the nucleation of ice Ih.

Criegee Intermediates React with Levoglucosan on Water.

Levoglucosan (Levo), a C6-anhydrosaccharide produced in the combustion of cellulosic materials, is the major component of aerosols produced from biomass burning over vast regions worldwide. Levo has long been considered chemically inert and thus has been used as a tracer of biomass burning sources. However, we now show that sugars including Levo, glucose, arabitol, and mannitol react rapidly with Criegee intermediates (CIs) generated during the ozonolysis of sesquiterpenes on the surface of water:acetonitrile microjets. Hydrophilic Levo reacts faster with CIs than with water or surface-active 1-octanol at air-aqueous interfaces. This unexpected phenomenon is likely associated with the relatively low water density at air-aqueous interfaces coupled with a higher gas-phase acidity of the saccharide hydroxyl groups (i.e., -OH) versus n-alkanols. Results presented herein show that aerosol saccharides are in fact reactive toward CIs. Given the abundance of saccharides in the atmosphere, they may be important contributors to the growth and mass loading of secondary organic aerosols.

Visualization and simulation of density driven convection in porous media using magnetic resonance imaging

Magnetic resonance imaging is used to observe solute transport in a 40cm long, 26cm diameter sand column that contained a central core of low permeability silica surrounded by higher permeability well-sorted sand. Low concentrations (2.9g/L) of Magnevist, a gadolinium based contrast agent, produce density driven convection within the column when it starts in an unstable state. The unstable state, for this experiment, exists when higher density contrast agent is present above the lower density water. We implement a numerical model in OpenFOAM to reproduce the observed fluid flow and transport from a density difference of 0.3%. The experimental results demonstrate the usefulness of magnetic resonance imaging in observing three-dimensional gravity-driven convective-dispersive transport behaviors in medium scale experiments.

Buoyancy‐driven coastal current blocks ventilation of an anoxic fjord on the Pacific coast of Canada

AbstractShallow sills restrict the ventilation of deep coastal fjords. Dense oceanic water seaward of the sill and lower density water within the receiving basin are generally required for oxygenated water to cross the sill and descend deep into the fjord. Here we use concurrent 10 year time series from current meters in the fjord and on the continental shelf to examine ventilation of the 120 m deep, anoxic inner basin of Effingham Inlet on the west coast of Vancouver Island. Whereas density currents traverse the 40 m deep sill and flow into the inner basin at mid‐depth at quasi‐fortnightly tidal intervals, only five current intrusions descended to the bottom of the basin over the decade‐long measurement period. The deep intrusions had a mean (±SD) return interval of 1.75 (±1.33) years and induced bottom‐water changes that persisted for 1–2 months. We show that, in addition to conditions within the inlet, deep ventilation of the inner basin is dependent on a coordinated sequence of external processes: (1) the onset of upwelling winds along the outer coast; (2) reversal of the buoyancy‐driven coastal current that normally flows poleward over the inner shelf off Vancouver Island; and (3) reversal of the estuarine circulation in the channel connecting the inlet to the ocean. As the observed ventilation intervals are short compared to the decadal intervals derived from the spacing of “homogenites” (sedimentation sequences disrupted by intruding bottom currents), the use of homogenites as proxies for past upwelling conditions in the northeast Pacific may need to be reexamined.

Flocculation of low algae concentration water using polydiallyldimethylammonium chloride coupled with polysilicate aluminum ferrite

ABSTRACTThe combined application of polydiallyldimethylammonium chloride (PDADMAC) and polysilicate aluminum ferrite (PSFA) was investigated to treat low algae density water samples, in which Microcystis aeruginosa is one of the dominant species. coagulation performance of M. aeruginosa was studied with regard to algal removal, Algal density was evaluated by determining the change in the optical density of the algal culture suspension at 680 nm and chlorophyll a. The dissolved organic matter, cellular morphology, viability, and recovery of M. aeruginosa cells after flocculation and sedimentation were also included. In addition, the effects of pH and addition order of PSFA and PDADMAC on algal removal were investigated. The removal efficiency of algae coagulated using combined PDADMAC and PSFA was improved by 34.5% and 19.3%, respectively. The organic matter removal was also enhanced. The optimum pH range for algal removal is 7.0–10.0, and the preferable addition sequence is the simultaneous addition of PDADMAC and PSFA. Scanning electron microscopy observation indicated that the combined usage of PDADMAC and PSFA caused no damage to the algal cell. Moreover, the experiment on algal recovery demonstrated that PDADMAC has bacteriostatic ability.

Upgrading fuel quality of moso bamboo via low temperature thermochemical treatments: Dry torrefaction and hydrothermal carbonization

The application of raw bamboo as biomass energy is restricted due to its large particle size, high oxygen content, low energy density and weak water resistance. In order to upgrade the fuel quality of moso bamboo, dry torrefaction (DT) and hydrothermal carbonization (HTC) have been investigated in this study. The physicochemical properties, thermal stability and microstructures of solid products were examined by varying the reaction temperature among 220, 260 and 300°C. The results showed that increasing temperature reduced the mass yield and energy yield, however, it significantly improved the calorific value of solid products. Through the HTC process, the bamboo hydrochar obtained the calorific value of 28.29MJ/kg, the energy yield of 59.77% and the fixed carbon content of 63.08% at the temperature of 260°C, indicating enhanced potential as a solid fuel. In comparison, the grindability (including particle size and bulk density), hydrophobicity, and thermal stability of torrefied bamboo were considerably lower than that of bamboo hydrochar produced at the same temperature. Furthermore, the transformation of chemical bonds demonstrated that hydrolysis, dehydration and decarboxylation took place during the HTC process. The porous structure was only slightly enhanced with increasing reaction temperature, exhibiting variation consistent with that of hydrophobicity.

Effect of Antioxidant Water on the Bioactivities of Cells.

It has been reported that water at the interface of a hydrophilic thin film forms an exclusion zone, which has a higher density than ordinary water. A similar phenomenon was observed for a hydrated hydrophilic ceramic powder, and water turns into a three-dimensional cell-like structure composed of high density water and low density water. This structured water appears to have a stimulative effect on plant growth. This report outlines our study of antioxidant properties of this structured water and its effect on cell bioactivities. Culturing media which were prepared utilizing this antioxidant structured water promoted the viability of RAW 264.7 macrophage cells by up to three times. The same tendency was observed for other cells including IEC-6, C2C12, and 3T3-L1. Also, the cytokine expression of the splenocytes taken from a mouse spleen increased in the same manner. The water also appears to suppress the viability of cancer cell, MCF-7. These results strongly suggest that the structured water helps the activities of normal cells while suppressing those of malignant cells.

Establishment of EEDI Baseline for Inland Ship of Bangladesh

Energy Efficiency Design Index (EEDI) [1] was introduced by the International Maritime organization (IMO) to stimulate innovation and technical development of all elements that increase the level of energy efficiency of a ship at design stage. Sea going ships over 400 gross tonnage are considered in the current regulation of EEDI. Inland ships are not covered by current EEDI regulations by IMO. As inland vessels share 0.6% of the global CO2 emission [2], the reduction attempt will not have bigger impact. But from the commercial point of view of a country the significance is very high, specially for under developed countries like Bangladesh. Inland self propelled ships face additional restrictions (shallow water/channel, low density water, restriction of ship's dimension, etc.) which increase the power requirement at the same speed, burning more fuel and emit more CO2. This paper is a continuation of the Ph.D research of the author where previous published paper's [3] results were updated and verified. The result of this paper would be one of the 1st attempts in the world was made to establish EEDI baseline for different types of self-propelled inland ships.

On the Perturbation Correction Factor &amp;lt;i&amp;gt;p&amp;lt;sub&amp;gt;cav&amp;lt;/sub&amp;gt;&amp;lt;/i&amp;gt; of the Markus Parallel-Plate Ion Chamber in Clinical Electron Beams

Purpose: All present dosimetry protocols recommend well-guarded parallelplate ion chambers for electron dosimetry. For the guard-less Markus chamber, an energy dependent fluence perturbation correction pcav is given. This perturbation correction was experimentally determined by van der Plaetsen by comparison of the read-out of a Markus and a NACP chamber, which was assumed to be “perturbation-free”. Aim of the present study is a Monte Carlo based reiteration of this experiment. Methods: Detailed models of four parallel-plate chambers (Roos, Markus, NACP and Advanced Markus) were designed using the Monte Carlo code EGSnrc and placed in a water phantom. For all chambers, the dose to the active volume filled with low density water was calculated for 13 clinical electron spectra (E0 = 6 - 21 MeV) and three energies of an Electra linear accelerator at the depth of maximum and at the reference depth under reference conditions. In all cases, the chamber’s reference point was positioned at the depth of measurement. Moreover, the dose to water DW was calculated in a small water voxel positioned at the same depth. Results: The calculated dose ratio DNACP/DMarkus, which according to van der Plaetsen reflects the fluence perturbation correction of the Markus chamber, deviates less from unity than the values given by van der Plaetsen, but exhibits similar energy dependence. The same holds for the dose ratios of the other well-guarded chambers. But, in comparison to water, the Markus chamber reveals the smallest overall perturbation correction which is nearly energy independent at both investigated depths. Conclusion: The simulations principally confirm the energy dependence of the dose ratio DNACP/DMarkus as published by van der Plaetsen. But, as shown by our simulations of the ratio DW/DMarkus, the conclusion drawn in all dosimetry protocols is questionable: in contrast to all well-guarded chambers, the guard-less Markus chamber reveals the smallest overall perturbation correction and also the smallest energy dependence.

Structure and dynamics of high- and low-density water molecules in the liquid and supercooled regimes.

By combining the local structure index with potential energy minimisations we study the local environment of the water molecules for a couple of water models, TIP5P-Ew and SPC/E, in order to characterise low- and high-density "species". Both models show a similar behaviour within the supercooled regime, with two clearly distinguishable populations of unstructured and structured molecules, the fraction of the latter increasing with supercooling. Additionally, for TIP5P-Ew, we find that the structured component vanishes quickly at the normal liquid regime (above the melting temperature). Thus, while SPC/E provides a fraction of structured molecules similar to that found in X-ray experiments, we show that TIP5P-Ew underestimates such value. Moreover, unlike SPC/E, we demonstrate that TIP5P-Ew does not follow the linear dependence of the logarithm of the structured fraction with inverse temperature, as predicted by the two-order parameter model. Finally, we link structure to dynamics by showing that there exists a strong correlation between structural fluctuation and dynamics in the supercooled state with spatial correlations in both static and dynamic quantities.

Molecular simulation study on K+–Cl− ion pair in geological fluids

This paper reports a classical molecular dynamics study of the potential of mean forces (PMFs), association constants, microstructures K+–Cl− ion pair in supercritical fluids. The constrained MD method is used to derive the PMFs of K+–Cl− ion pair from 673 to 1273 K in low-density water (0.10–0.60 g/cm3). The PMF results show that the contact ion-pair (CIP) state is the one most energetically favored for a K+–Cl− ion pair. The association constants of the K+–Cl− ion pair are calculated from the PMFs, indicating that the K+–Cl− ion pair is thermodynamically stable. It gets more stable as T increases or water density decreases. The microstructures of the K+–Cl− ion pair in the CIP and solvent-shared ion-pair states are characterized in detail. Moreover, we explore the structures and stabilities of the KCl–Au(I)/Cu(I) complexes by using quantum mechanical calculations. The results reveal that these complexes can remain stable for T up to 1273 K, which indicates that KCl may act as a ligand complexing ore-forming metals in hydrothermal fluids.